Forced air cooled refrigerator



March 3l, 1964 F. A. scHUMAcHL-:R 3,126,717

' FORCED AIR cooLED REFRIGERATOR Filed Deo. 12,'1962 n --J lull ummmmum. ...qu

INVENTOR. FRANK A. scHuMAcHER Hls ATTORNEY United States Patent O Thepresent invention relates to household refrigerators of the type inwhich an above freezing and a below freezing storage compartment arecooled by air circulated over an evaporator positioned outside thecompartments and is more particularly concerned with an improved aircirculation and temperature control arrangement for such refrigerators.

When air circulated over a single evaporator is employed for coolingboth an above freezing storage compartment and a below freezing storagecompartment, it is necessary to operate the evaporator somewhat belowthe temperature desired in the lower temperature compartment. Since theair leaving the evaporator is at a much lower temperature than thatdesired in the higher temperature or above freezing compartment, meansmust be provided for so proportioning the air flow to the twocompartments that the amount of air provided to the above freezingstorage compartment is just sufiicient to maintain the desiredtemperatures therein. In such refrigerators it is also desirable toprovide means for separately controlling the temperatures in each of thetwo storage compartments so that the user has some flexibility in thetemperatures at which the respective compartments operate.

The present invention has as its principal object the provision of arefrigerator in which separate storage compartments operating atdifferent temperatures are cooled by air circulated over a singleevaporator, the refrigerator including means providing for a limitedchange in the operating temperature of either compartment independent ofthe temperature maintained in the other compartment.

lt is another object of the present invention to provide atwo-temperature refrigerator cabinet including new and improved controland air circulating means.

A further object of the invention is to provide a household refrigeratorcomprising an above freezing storage compartment and a below freezingstorage compartment in which the controls for regulating thetemperatures in both compartments are positioned in a readily accessibleposition in the above freezing compartment.

Further objects and advantages of the present invention will becomeapparent as the following description proceeds and the features ofnovelty which characterize the invention will be pointed out withparticularity in the claims annexed to and forming a part of thisspecification.

ln accordance with a preferred embodiment of the present invention,there is provided a household refrigerator including an above freezingstorage compartment, a freezer or below freezing storage compartment andan insulated evaporator compartment below and separate from the twostorage compartments. The evaporator compartment is designed to receivea single evaporator forming part of a refrigerating apparatus which alsoincludes a condensing unit comprising a compressor and a condenser. Fanand air circulating means is provided for withdrawing air from both ofthe storage compartments and circulating it over the evaporator unit.Most of the cooled air circulated over the evaporator unit is conductedby means of a first supply duct to the below freezing compartment. Asecond supply duct connected to this first duct conducts a portion ofthe cooled air to the above freezing compartment. The operation of thecompressor and the air circulating fan is controlled by a thermostatpositioned in the above freezing compartment and including a controlbulb responsive to a temperature condition in ICC that compartment. Thethermostat is thus an above freezing compartment control and is designedto hold the temperature of that compartment within the desired operatinglimits. Variable air ow control means associated with the outlet fromthe second supply duct provides means for varying the amount of airflowing through the second supply duct to the above freezing compartmentand thereby changing the proportion of cooled air circulated through thefreezer compartment. Thus a decrease in the amount of air flowing to theabove freezing compartment by adjustment of the air flow control meanscauses the compressor to run longer in order to satisfy the requirementsof the above freezing storage compartment thermostat thereby causing thebelow freezing compartment to become colder. Conversely, adjustment ofthe variable air flow control means to a more open position therebyadmitting more refrigerated air to the above freezing compartment causesthe thermostat to reach the compressor cut off temperature sooner withthe result that the freezer storage compartment runs at a somewhathigher temperature again without affecting the temperature maintained inthe above freezing compartment. Preferably both the thermostatadjustment means and the air iiow control means are placed adjacent oneanother on one wall of the above freezing storage compartment so thatboth are readily accessible to the user.

For a better understanding of the invention, reference may be had to theaccompanying drawing in which:

FIGURE 1 is a front elevation, with the closure members removed, of ahousehold refrigerator including what is presently considered to be apreferred embodiment of the present invention;

FlGURE 2 is a horizontal sectional view taken generally along line 2 2of FIGURE l;

FIGURE 3 is a vertical sectional view of a portion of the cabinet ofFIGURE l taken generally along line 3 3 of FIGURE l;

FIGURE 4 is a vertical sectional view taken along line 4 4 of FIGURE 3;and

FIGURE 5 is a diagram of a portion of an electrical control circuit forcontrolling the operation of the refrigerator.

Referring to FGURE l, there is shown a refrigerator cabinet including anouter shell 1 and upper liner 2 and a lower liner 3 spaced from theshell 1 and from one another, the space between these members beingfilled with suitable heat insulating material. The upper liner 2 forms afresh food or above freezing storage compartment 4 while the lower liner3 defines a below freezing or frozen food storage compartment 5. Anevaporator compartment 6 and a condensing unit compartment 7 arepositioned in side-by-side relationship along the bottom portion of thecabinet below the freezing compartment 5. For clarity the closuremembers for closing the access openings to the two storage compartmentsand to the evaporator and condensing unit compartments have been omittedfrom FEGURE l. A removable unitary refrigerating apparatus forrefrigerating the air supplied to the storage compartments 4 and 5comprises a condensing unit which is positioned in the condensing unitcompartment 7 and which includes a compressor 9, a condenser 10 and afan 11 designed to pass a cooling stream of air over the condenser andthe compressor. Connected to the condensing unit by means of a frame 12is an evaporator unit disposed within the evaporator compartment 6 andincluding an evaporator 14 which comprises a length of tubing folded toprovide a plurality of horizontal passes and a housing 15 which dividesthese passes into a frost collecting evaporator portion 16 and a coolingportion contained within the housing 1S. A fan 17 mounted on the frontof the housing 15 is adapted to draw air into the evaporator compartmentfrom the storage compartments and direct air over the cooling evaporatorportion contained within the housing 15 after which the cooled air isreturned by suitable ducts 19 and 24 to the two compartments 4 and 5. Itwill be understood that means, not shown, are also provided forperiodically defrosting the evaporator unit.

For the purpose of maintaining the freezer compartment 5 at desiredsub-freezing temperature, there is provided means defining an air owpath which includes, in addition to the cooling portion of theevaporator 14, the supply duct 19 extending from the rear of the housing15 upwardly through the rear wall 20 of the cabinet and having an outlet22 opening into the freezer compartment 5 and an air return passage 23.The outlet 22 may be provided with suitable louvers for directing theflow of air through the compartment 5. After passing through the freezercompartment 5, the air is returned to the evaporator compartment througha return passage 23 provided in the bottom wall of the freezercompartment irnmediately above the fan 17 whereby the return air fromthe freezer compartment passes directly through the cooling portion ofthe evaporator contained within the housing without passing over thedefrost collecting portion 16.

For the purpose of supplying cooled air to the above freezing storagecompartment 4, there is provided a second air ow path including thesecond supply duct 24 extending upwardly from the supply duct 19 to thetop of the above freezing storage compartment 4. This supply duct 24which in the illustrated embodiment of the invention is a continuationof the duct 19 supplying air to the freezer compartment has its outlet25 opening through the rear wall 26 of the liner 2 adjacent one topcorner of the above freezing compartment 4. Air is withdrawn from alower portion of the above freezing storage compartment 4 through anopening 27 which is connected by means of duct 28 to the rear of theevaporator compartment 6. The return air from the above freezing storagecompartment 4 passes over the frost collecting portion 16 of theevaporator where the moisture contained therein is removed before it isagain mingled with the air returning from the freezer compartment 5through the opening 23.

By this air flow system, it will be seen that the below freezingcompartment 5 is cooled by air owing in a closed circuit from theevaporator through the duct out through the supply opening 22 and backto the cooling portion of the evaporator through the opening 23. Theabove freezing compartment 4 is cooled by a portion of the air flowingfrom the evaporator into the duct 19 which is bypassed into the abovefreezing compartment 4 through the duct 24.

In accordance with the present invention, the operation of thecompressor 9 and the fan 17 is controlled by a thermostat 30 mounted inthe above freezing storage compartment 4 and including a control dial 31and a sensing bulb 32. While the bulb 32 may be positioned at any pointin the fresh food compartment where it will sense a temperatureaccurately reflecting the storage temperature conditions maintained inthat compartment, it is preferably positioned on the rear wall 26 of theliner 2 adjacent air outlet 25.

The amount or proportion of air flowing from the evaporator to the abovefreezing storage compartment 4 when fan 17 is running is regulated bymeans of a damper 33 slidably mounted on the rear wall 26 for varyingthe amount of refrigerated air supplied to the compartment 4 throughopening 25. As shown in FIGURE 4 of the drawing, the opening ispreferably triangular in shape so that there is obtained a rather linearcontrol or proportioning of the air flowing to the fresh foodcompartment as the damper 33 is moved from its left hand or openposition to its right hand position in which it partially closes theopening 25. By this arrangement the indicia 35 on the face of the damperframe 36 can be linear and accurately reflect the change in temperaturesobtained by movement of the damper 33 to its various positions.

Since air not permitted to flow into the above freezing compartment 4through opening 25 circulates instead through the compartment 5, it willbe seen that when the damper 33 is in its fully open position a minimumamount of air will ow through the below freezing compartment 5 Whilemovement of the damper 33 towards its closed position will increase theproportion of air flowing into the compartment 5.

Thus independent control of the operating temperatures of thecompartments 4 and 5 is obtained by means of the thermostat 30 and thedamper 33. Since the thermostat 30 is responsive to a temperaturecondition in the above freezing compartment 4, the compressor will becycled on and off in accordance with the temperatures sensed in thatcompartment. The desired temperature range within the compartment 4 willbe maintained regardless of the setting of the damper 33, the onlydifference being that the compressor will be run for a longer period oftime to satisfy the requirements of the thermostat 30 when the damper ispartially closed than when it is fully open. On the other hand, thesetting of the damper 33 directly affects the temperature maintained inthe freezer compartment 5. When the damper 33 is opened so that themaximum amount of air possible is being supplied to the above freezingcompartment 4, a smaller proportion of the air will flow through thecompartment S so that a higher temperature is maintained in thatcompartment although, of course, this temperature will still be belowfreezing due to the fact that the air supplied from the evaporator unitis at a below freezing temperature. Movement of damper 33 to a flowrestricting position decreases the amount of air flowing to thecompartment 4 and correspondingly increases the amount of air flowingfrom the evaporator through the freezer compartment 5. The compressorthen operates for a longer period of time to satisfy the requirements ofthe thermostat 30 with the result that the cooled air from theevaporator will be circulated for a longer period of time through thefreezer compartment 5 and thereby cause this compartment to reach asomewhat lower temperature.

As is shown in FIGURE l of the drawing, this air flow and control meanspermits the positioning of both controls in the fresh food storagecompartment where they are easily accessible for regulating thetemperatures in either of the two storage compartments.

Preferably, the sensing bulb or capillary 32 is positioned on and inheat exchange relation with the rear wall 26 of the liner 2 to one sideof the air delivery opening 25. In this position, due to the heatleakage through the insulation adjacent the rear wall 26, the sensingbulb will reflect the temperature of a part of the above freezingcompartment which passes through a substantial temperature fluctuationduring each cycle of operation of the compressor. During the compressorolf period, the wall 26 will tend to warm to a greater extent than theshelves and other storage areas within the compartment 4 While duringcompressor on periods it will be cooled by the cold air entering thecompartment. Thus the thermostat 30 can be of the less critical typepermitting a greater temperature fluctuation between the on and offsettings than would be the case if the bulb 32 were suspended directlyin the air contained within the compartment 4. Also by positioning thebulb on the rear wall 26 behind a shield 40 the bulb is protected fromthe warming elfects of too many door openings.

In order that the bulb will anticipate the temperature at which thecompressor should be turned off, a small portion of the air issuingthrough the inlet 25 is preferably directed through an opening 41 behindthe grille or face plate 36 over that area of the wall 26 surroundingthe bulb 32. This portion of refrigerated air is just sufficient to coolthe bulb 32 during a compressor on cycle to the point that thethermostat stops the compressor at approximately the time that the mainvolume of air passing into the compartment 4 through the opening 25 hascooled the contents of that compartment to the desired temperature.

While there has been shown and described a particular embodiment of thepresent invention, it will be understood that the invention is notlimited thereto and it is intended by the appended claims to cover allsuch changes and modifications as come within the true spirit and scopeof the invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A refrigerator including an above freezing compartment, a belowfreezing compartment and an evaporator compartment including anevaporator separate from said above and below freezing compartments,

a refrigerating system including a compressor and said evaporator,

means including a fan and a first supply duct connecting said evaporatorcompartment with said freezer compartment for circulating air in a firstair flow path from said evaporator through said supply duct to saidfreezer compartment and back to said evaporator,

means including a second supply duct connected to said first supply ducthaving an outlet opening into said above freezing compartment forcirculating a portion of the air flowing through said first supply ductto said above freezing compartment and back to said evaporator,

compressor and fan control means responsive only to a temperature in theabove freezing compartment for controlling the operation of saidcompressor and fan to maintain a predetermined temperature in said abovefreezing compartment,

variable air flow control means associated with said outlet opening forvarying the amount of air fowing from said second supply duct andthereby controlling the proportion of air circulated through said belowfreezing storage compartment to vary the temperature of said belowfreezing compartment,

said temperature sensing means being arranged to sense the temperatureof a wall area of Said above freezing compartment adjacent said opening,

and means for directing a portion of the air vpassing through saidopening over said wall area.

2. A refrigerator including an above freezing compartment, a belowfreezing compartment and an evaporator compartment including anevaporator separate from said above and below freezing compartments,

a refrigerating system including a compressor and said evaporator,

means including a first supply duct connecting said evaporatorcompartment with said freezer compartment defining a rst air flow pathfor circulating air from said evaporator through said supply duct tosaid freezer compartment and back to said evaporator,

means including a second supply duct having its inlet connected to saidfirst supply duct and its outlet opening into said above freezingcompartment for circulating a portion of the air flowing through saidfirst supply duct to said above freezing compartment and back to saidevaporator,

fan means for circulating said air,

compressor and fan control means including temperature sensing meansresponsive only to a temperature in the above freezing compartment forcontrolling the operation of said compressor to maintain a predeterminedtemperature in said above freezing compartment,

and variable air flow control means associated with said outlet openingfor varying the amount of air flowing through said second supply ductand thereby controlling the proportion of air circulated through saidbelow freezing storage compartment;

said temperature sensing means being arranged to sense the temperatureof a wall area of said above freezing compartment adjacent said opening,

and means for directing a portion of the air passing through saidopening over said wall area.

3. A refrigerator including an above freezing compartment, a belowfreezing compartment and an evaporator compartment including anevaporator separate from said above and below freezing compartments,

a refrigerating system including a compressor and said evaporator,

means including a first supply duct connecting said evaporatorcompartment with said freezer compartment defining a first air flow pathfor circulating air from said evaporator through said supply duct tosaid freezer compartment and back to said evaporator,

means includinga second supply duct connected to said first supply ductand having an outlet opening into said above freezing compartment forcirculating a portion of the air flowing through said first supply ductto said above freezing compartment and back to said evaporator,

a fan for circulating said air over said evaporator and into said firstsupply duct,

compressor and fan control means including temperature sensing meansresponsive only to a temperature in the above freezing compartment forcontrolling the operation of said compressor to maintain a predeterminedtemperature in said above freezing compartment,

variable air flow control means associated with said outlet opening forvarying the amount of air fiowing through said second supply duct andthereby controlling the proportion of air circulated through said belowfreezing compartment to vary the temperature of the below freezingcompartment,

said temperature sensing means being arranged to sense the temperatureof a wall area of said above freezing compartment adjacent said outletopening,

and means operable independent of said air flow control means fordirecting a fixed portion of the air passing through said outlet openingover said wall area.

References Cited in the le of this patent UNITED STATES PATENTS

1. A REFRIGERATOR INCLUDING AN ABOVE FREEZING COMPARTMENT, A BELOWFREEZING COMPARTMENT AND AN EVAPORATOR COMPARTMENT INCLUDING ANEVAPORATOR SEPARATE FROM SAID ABOVE AND BELOW FREEZING COMPARTMENTS, AREFRIGERATING SYSTEM INCLUDING A COMPRESSOR AND SAID EVAPORATOR, MEANSINCLUDING A FAN AND A FIRST SUPPLY DUCT CONNECTING SAID EVAPORATORCOMPARTMENT WITH SAID FREEZER COMPARTMENT FOR CIRCULATING AIR IN A FIRSTAIR FLOW PATH FROM SAID EVAPORATOR THROUGH SAID SUPPLY DUCT TO SAIDFREEZER COMPARTMENT AND BACK TO SAID EVAPORATOR, MEANS INCLUDING ASECOND SUPPLY DUCT CONNECTED TO SAID FIRST SUPPLY DUCT HAVING AN OUTLETOPENING INTO SAID ABOVE FREEZING COMPARTMENT FOR CIRCULATING A PORTIONOF THE AIR FLOWING THROUGH SAID FIRST SUPPLY DUCT TO SAID ABOVE FREEZINGCOMPARTMENT AND BACK TO SAID EVAPORATOR, COMPRESSOR AND FAN CONTROLMEANS RESPONSIVE ONLY TO A TEMPERATURE IN THE ABOVE FREEZING COMPARTMENTFOR CONTROLLING THE OPERATION OF SAID COMPRESSOR AND FAN TO MAINTAIN APREDETERMINED TEMPERATURE IN SAID ABOVE FREEZING COMPARTMENT, VARIABLEAIR FLOW CONTROL MEANS ASSOCIATED WITH SAID OUTLET OPENING FOR VARYINGTHE AMOUNT OF AIR FLOWING FROM SAID SECOND SUPPLY DUCT AND THEREBYCONTROLLING THE PROPORTION OF AIR CIRCULATED THROUGH SAID BELOW FREEZINGSTORAGE COMPARTMENT TO VARY THE TEMPERATURE OF SAID BELOW FREEZINGCOMPARTMENT, SAID TEMPERATURE SENSING MEANS BEING ARRANGED TO SENSE THETEMPERATURE OF A WALL AREA OF SAID ABOVE FREEZING COMPARTMENT ADJACENTSAID OPENING, AND MEANS FOR DIRECTING A PORTION OF THE AIR PASSINGTHROUGH SAID OPENING OVER SAID WALL AREA.